Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	[1]	$ 791.0	$ 564.5	$ 1,369.1	$ 2,185.5
Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		289.3	178.5	516.1	746.7
Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		193.4	108.3	321.5	415.8
Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		81.4	37.5	138.8	184.2
Oilfield
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		79.0	28.7	132.2	189.5
Public authorities and street light
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		71.1	37.0	119.1	160.1
System sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		714.2	390.0	1,227.7	1,696.3
Provision for tax refund
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		(2.1)	0.0	(2.7)	0.0
Integrated market
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		43.0	128.3	65.8	430.4
Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		32.9	36.7	68.7	73.0
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		$ 3.0	$ 9.5	$ 9.6	$ (14.2)

[1] In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. Operating revenues for the six months ended June 30, 2021 significantly increased due to increased fuel, purchased power and direct transmission expenses, which are generally recoverable from customers, as a result of Winter Storm Uri. For further discussion, see Note 14 and "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operation."